Artificial limbs, including leg prostheses, employ a wide range of technologies to provide solutions suitable to many differing needs. For a trans-femoral amputee, basic needs in a leg prosthesis include stability, while standing and during the stance phase of a walking gait, and mechanical compatibility with the walking (or running) gait and some manner of knee flexion during stance and swing phases of a gait.
Certain trade-offs exist between security and stability, and walking or running performance (dynamic behavior). A simple, non-articulable leg (having no movable knee), may provide maximum stability, but does not provide for an ideal gait. Also, sitting may be awkward if a person cannot bend their knee.
There are no prosthetic knees tailored for high activity users, particularly athletes. For example, above-the-knee amputee sprinters and runners typically must resort to prosthetic knees designed primarily for walking purposes. From the selection of walking knees, the amputee engaged in athletic activities must compromise performance and durability of the knee.